Differential froth flotation of sulfide ores



ratemea Dec. 27, 1949 DIFFERENTIAL FROTH FIDIATION OF SULFIDE OBES Charles M. Nokes, Salt Lake cm, Charles guimgley, Garfield, and Robert '1. Prlng, Mann,

No Drawing. Application October 16, 1948, Serial No. 55,014

Claims. (Cl. 209-167) This invention relates to a process of froth flotation in which certain metalliferous sulfides are depressed by means of novel inorganic chemical agents or compounds exhibiting a selective depressing action for the sulfides.

In the flotation of sulfides and certain precious metals such as gold and'silver which behave toward sulfide collectors in the same manner as sulfides, it is sometimes desirable to remove certain materials which have the property of floating with oily collectors or frothers which are hydrocarbons or water-insoluble alcohols or mixtures thereof. The most important minerals of this class are molybdenite, graphite and carbons. Another group of minerals comprises some of the hydrous magnesium or aluminum-containing silicates which exhibit strongly hydrophobic surfaces. The principal minerals of this class are the various talcs, sericite, the micas and pyrophillite. Chlorites for-the most part are only weakly hydrophobic and are unsuitable for the processes of the present invention although there are occasional chlorites which exhibit a greater water-repellency and are about on the borderline of utility. These minerals, although chemically quite different, behave identically in froth flotation and are characterized by ready fioatability withhydrocarbon collectors or alcohol collectors hol collectors and frothers also show some collecting activity for the sulfide minerals and prevent a sharp separation. An even more serious 2 phates or the like. The presence of small amounts of the original sulfide collector enhances the tendency of the sulfides to float and makes the separation of molybdenite. carbon or strongly hydrophobic hydrous silicates containing magnesium or aluminum from such concentrates even more difiicult than in the case of original ores. V

The present invention is based on our discovery that inorganic compounds of phosphorus, arsenic and antimony containing oxygen and sulfur in the bivalent state exert a strong depressant action on sulfide minerals other than molybdenite in the presence of hydrocarbon and alcohol collectors and depress these minerals so vigorously that even in the presence of sulfide promoters it is possible to float molybdenite, carbons and strongly hydrophobic hydrous silicates containing magnesium or aluminum away from the sulfides without serious contamination of the concentrate by the sulfides and with a high degree of removal of the molybdenite, carbons and strongly hydrophobic hydrous silicates containing magnesium or aluminum.

The exact chemical composition of the novel depressants has not been fully determined and it is possible that in some instances at least they are not a single pure compound but are mixtures. They are, however. characterized, in addition to phosphorus, arsenic or antimony respectively, by the presence of bivalent sulfur, oxygen and a cation. In the initial preparation of the depressants, the cation is ammonium or an alkaliforming metal. The depressants may be used as such or they may be transformed into their corresponding heavy metal compounds by reproblem is presented by the fact that, chemically, molybdenite, graphite and carbons and strongly hydrophobic hydrous silicates containing magnesium or aluminum: may have to be removed from bulk sulfide or precious metal concentrates. This is due to the met that molybdenite and carbons are often present in comparatively small amounts which makes a preliminary bulk sulfide float necessary. Talc and mica also are often-present in sulfide concentrates and a high degree of-removal'is economically desirable. However, the problem of separation by fiotation is greatly complicated in the case of such concentrates because they usually contain the residue of the sulfide flotation collectors used in fioatingxconcentrates. For example, they may contain xanthatcs, dithiophosaction with a heavy metal salt. For example, they may be transformed into copper compounds by reaction with copper sulfate or into simple compounds of iron, lead, chromium, aluminum or molybdenum by reacting with ferrous sulfate,

lead nitrate, chromium nitrite, aluminum sulfate and ammonium molybdenite. The frothers and.

frothers. such as mixtures of higher paramn al-' cohols and hydrocarbons. It should be noted that the depression efiected pressants are 'possible.

by the novel agents of the present invention may be temporary or permanent depending on the specific requirements in any individual case. Thus, for example, if the original ore is treated which contains sulfides and either molybdenite. carbons, or strongly hydrophobic hydrous silivates containing. magnesium "or aluminum, the first fioat will be effected in the presence of a hydrocarbon and/or alcohol frother or collector with the sulfides temporarily depressed by the novel reagents of the present invention. There-' after, the sulfides in the tailing may be actifinal flotation step.

A number of methods of preparing the de- Typical reactions are the following:

Thiophosphoryl chloride and sodium hydroxide Thiophosphoryl chloride and calcium hydroxide Thiophosphoryl chloride and sodium silicate Thiophosphoryl chloride and sodium carbonate Thiophosphoryl chloride and ammonium hydroxide Thiophosphoryl chloride and ammonium phosphate Thiophosphoryl chloride and sodium phosphate Thiophosphoryl chloride and sodium borate Phosphorus sulfides and sodium hydroxide Phosphorus sulfides and calcium hydroxide Phosphorus sulfides and sodium silicate Phosphorus sulfides and soduim carbonate Phosphorus sulfides and ammonium hydroxide Phosphorus sulfides and ammonium carbonate Phosphorus sulfides and ammonium phosphate Phosphorus sulfides and sodium phosphate 4 Phosphorus sulfides and sodium borate Phosphorus sulfides and calcium cyanide Phosphorus sulfides and sodium cyanide Arsenic sulfide and sodium hydroxide Arsenic sulfide and potassium hydroxide Arsenic sulfide and calcium hydroxide Arsenic oxide, sulfur and sodium hydroxide Arsenic oxide, sulfur and potassium hydroxide Antimony oxide, sulfur and sodium hydroxide Antimony oxide, sulfur and potassium hydroxide vantage that it can be shipped more readily and economically than can the wet slurries. The

form in which the depressants of the present invention will be used in any particular case' is largely a matter of economies. In some instances it is cheaper to prepare the depressant at the place of use. In other cases, shipment of the dry material prepared at a central point is more economical. The possibility of use of the depressants of the present invention in these Various forms adds greatly to the flexibility of the process of recovering molybdenum, carbon or strongly hydrophobic hydrous silicates containing magnesium or aluminum and is one of the 5 additional advantages of the invention.

When bulk sulfide concentrates are treated, it is often of advantaye to subject the concentrate to a preliminary treatment with acid and alkali; for example, sulfuric or sulfurous acids and then lime. This often removes frother collector coatings from the minerals and aids in the subsequent selective separation. Other mineral acids may be used such as hydrochloric acid. The sequence of treatment appears more or less immaterial. Thus the acid conditioning may be first or an alkaline conditioningwith alkali may precede it. "1 when treatment withacid and alkali is used on a concentrate, the addition of the depressant, collector, and frother, if necessary, are ordinarily made after the acid and alkali conditioning is completed.

We have found that in moylbdenite fiotations somewhat improved results are obtainable if the ore is conditioned before floating with a salt of a polyvalent metal, particularly a salt of calcium such as calcium chloride. This conditioning is in place of the treatment with acid described above.

The invention will be described in the following specific examples which set forth the preparation of typical depressants and their use in the process of the present invention.

EXAMPLE 1 40 gm. of sodium hydroxide (NaOH) is dissolved in 80 ml. water.- gm. of thiophosphoryl chloride is added to the solution, the entire contents being shaken until all thiophosphoryl chloride has reacted. This may require as long as two or three hours, depending upon the intensity of agitation.

EXAMJPLEZ' 13 gm. of sodium hydroxide is dissolved in 75 ml. of water. 10 gm. of phosphorus sulfide (chiefly P255, but containing other homologues among which may be P483) is added slowly to the solution so as to keep the reacting temperature under control. This reaction proceeds rapidly, 50 being completed in about 5 minutes.

EXAMPLES 12 gm. of calcium oxide (CaO) is reacted with 50-80 ml. of water. To the slurry is added 10 gm.

of phosphorus sulfide (chiefly P285) and the mass vigorously stirred at 70-75 C. until reaction is complete.

EXAMPLE 4 To 7 parts by weight of sodium hydroxide (NaOH) add 4 parts by weight of sulphur (S) and 5 parts by weight of water. Stir and heat until all sulfur has gone into solution (that is combined with the sodium hydroxide in aqueous solution). Adding a small amount of additional water, as heating continues, generally facilitates the dissolution of the sulfur. After all sulfur is in solution, add sufiicient water to bring the total water added up to parts by weight. Then add 70 8 parts by weight of arsenic trioxide (AS203) and boil until the reaction is complete. The quantities of sodium hydroxide, sulfur, and arsenic trioxide may vary within certain limits without decreasing the 'efiiciency of the resulting depressant beyond the point of practicability.

V add 25 parts by weight of water.

boiling solution add small increments of sulfur amass EXAMPLE 5 To parts by weight of arsenic sulfide add 11.6 parts by weight of lime (CaO) add '15 ml. of water and boil; finally dilute to the desired concentration.

EXAMPLE 6 To 7 parts by weight of potassium hydroxide, Boil. To the alternating with small increments of antimony trioxide until a total of Zparts by weight of sulfur and 10 parts by weight of antimony trioxide have been added.

EXAMPLE '1 A material obtained by flotation concentration 10 m1. sulfuric acid (commercial)66 B. 12 gm. calcium oxide (commercial) 250 ml. depressant of Example 3 drops kerosene The pulp was thoroughly agitated in a minerals separation flotation machine after the-addition of each of the agentaand the pH values were taken after the incorporation of the first three and a the conclusion of the roughing period. I

pH after calcium oxide addition 11.6 pH after sulfuric acid addition 6.6 pH after depressant of Ex. 3 addition 9.9 pH at end of roughing period 9.7

, Flotation (10 minutes floating time) produced a rougher concentrate, a middling and a rougher tailing. The rougher concentrate was cleaned twice in a Fagergren flotation machine making a first cleaner tailing, a second cleaner tailing, and a cleaner concentrate. Most of the sulfides of copper and iron were depressed in the flotation machine and drawn of! as rougher tailing, while most of the molybdenite was removed as a froth concentrate. The Fagergren flotation machine was used for grading up or cleaning the flotation machine rougher concentrate.

The'eifectiveness of this invention treating a flotation concentrate containing molybdenite and other sulfides such as those of copper and iron for the selective flotation separation of molybdenite from other sulfides, may be seen from the following metallurgical data.

Suitably ground material (Utah Copper Company, Arthur Plant Crude Ore Heading) was treated in a 5000-gram minerals separation flota- (dry basis) of ore and water were added the following agents:

5 ml. depressant '01 Ex. a (00.0, m0. P280) 6 dps. burner oil 6 dpe. frother consisting of a mixture of alcohols from 7 to 10 carbon atoms.

The pulp was thoroughly agitated and a rougher molybdenite concentrate was removed as a froth concentrate. This concentrate was later cleaned in a l 'agergren flotation machine to form (1) molybdenite cleaner tailing; (2) molybdenite cleaner concentrate. To the material remaining in the minerals separation flotation machine were added 3 mi. of 2.5 per cent xanthate solution, and arougher copper concentrate was removed as a iroth concentrate. (xanthate is the copper collector used to float the copper after the flotation of the molybdenite.) This concentrate was later cleaned in a Fagergren flotation machine to form (3) copper cleaner tailing, (4) copper cleaner concentrate. The tailing (5) was removed from the machine as waste material.

The results of the test just described may be seen from the following metallurgical tabulation:

Suitably ground material (Utah Copper Company. Arthur Plant, general flotation concentrate) was treated in a laboratory Fagergren flotation machine. To the charge of about 500 gm.

(dry basis) of concentrate and water were added the following agents in amounts designated:

In the flotation that followed, substantially all the molybdenite was removed as a froth concentrate, making (1) a rougher tailing and a rougher concentrate. The rougher concentrate was cleaned making (2) a cleaner tailing, and (3) a cleaner concentrate containing substantially all the, molybdenite, the depressed copper and iron sulfides remaining in the rougher tailing.

The results of this test are given in the following metallurgical tabulation:

Suitably ground material (Utah Copper Comtion machine. To the charge of about 5000 gms. mm. Plant, general flotation concen P c t Per Cent Assays Per Cent Distr. er en mu I v Cu M05: Cu M08;

25ml. of the reaction product (31m;

. H20 and 1 gm. arsenic sulflde) made upyto 50 ml.for testing ,g-dps. moly deni i 1ed In the flotatitih that followdffifib talltl aliy all the molybdenite was removed ashlffothconcentrate, making (1) a rougher tailing an'darougher concentrate. The rougher concentrate was cleaned, making (2) a cleaner tailing and (3) a cleaner concentrate containing Substantially all the molybdenitc, the depressed copper and iron sulfides remaining in the rougher; tailing.

' collector "(Marita-airmai- Fourth-Adding to the pulp in the flotation machine 0.30 gn1..oicopper sulfate, 0.075 gm. of .xanthate and 2 dps. of frother consisting of: a mixture of parafllne alcohols from ,5 to wcarbon atoms, thereby recovering the zinc asa rougher froth concentrate, the rougher tailing (pulp remaining in the machine) being considered waste and drawn out of the machine. The rougher concentrates may be graded up as desired by methods known to the art.

EXAMPIE 12 The following test shows that by the use -oi this invention it is feasible to concentrate by flotation, ore containing molybdenum sulfide, copper sulfide, lead sulfide, and gangue obtaining three separate concentrates: a' molybdenite concentrate, a copper concentrate and a'lead concentrate.

Material, Assay, Per Cent Distribution, Per Cent Product Per pent MOS; Cu Pb Mos, -Cu Pb Heading Computed). 100.00 0. 000 0.971 5. 012 100.00 100.00 100.00 Rougher ailin 88.15 '.0a4 0.055 .06 4.00 5.25 1.00 RoughcrMoS; onc-- 1.30 40.800 1.100 1.35 87.02. 1.60 .24 Rougher Cu Conc 5. 52 670 10. 700 .05 6.08 67. 39 1.50 Roughcr Pb C0nc. 10.03 .140 2.250 48.60 2.30 "25.76 97.20

The results of this test may be seen from the I following metallurgical tabulation; so I Procedure I First-4500 gin. ore ground in laboratory ball Fe Co t ssa' s PcrCentDistr. Percent n y mill,using 0.22 gm.l1me (CaO).

on Mos Cu Mos: Sec0nd.-Pulp subjected-to flotation using a Fagergren laboratory flotation machine adding 100500 1,71; 1,1 10003 1 5 ml. of the depressant of Ex. 3,-2 dps. of burner R hTali 83.68 31.50 .040 9.1 2.. oiflelzlliegl'Taiiin g 14-17. no 2280 IMG 2226 011 and 3 dps. of frother consisting of a nnxture Cleaner Concentr 1.95 -120- :.0s.-100 .25 15.40 of parafline alcohols from5 to 10 carbon atoms, thereby recovering the molybdenite as arougher EXAMPLEll m froth concentrate.

The follow'ingftest showsftlija't by the use of this invention, it is feasibleto"concentrate by flotation an ore containing molybdenum sulfide, copper sulfide, zinc-sulfidmand -gangue, obtainingthree separate concentrates: a: molybdenite concentrate, a copperconcentrate and a zinc concentrate.

Third.Adding to the pulp in the flotation ma chine 0.16 gm. .xanthate and 2 dps. -of frother consisting of a-mixture of paraflinealcohols from 5 to 10 carbon atoms,-thereby recovering the copper in the formof a rougher froth concentrate.

Fourth.Adding to thepulpin'the flotation Materm Assay lcr- Cent -Distribution,Per Cent Product Perpent a p ll llo sr Cu Zn MOS: -Cu Zn Heading (Computed). 100.00 0. 32s 0.856 3 554 100.00 100.00 100.00 Rougher Tfliliilg. 88.03 .014 .060 .08 3.66 6. 19 1.97 Roughcr MoS1Cnnc. '.1.29 "20.700 2.400 3.500 81.41 3.63 1.27 Rougher Cu Conc 5.14.. -.86 .13. 750 2.90 13.-l1 82.50 4.19 Rougher Zn Cone I 5.54 .09: 1.175 49.40 1.52 7.59 02.57

adequ te-j machine 0.05 gm. xanthate, 0.10 gm. of copper First-500 gm. ore ground in more... ball mill using 0.22 gm. lime (.CaO).

Second-Pulp subjected to flotation using a Fager'gren laboratory flotation machine adding 5 ml. of the depressant of Ex. 3, 3 dps. of burner oil and 2 dps. of frother consisting of a mixture of aliphatic alcohols from 7 to 10 carbon atoms, thereby recovering the molybdenite (MoS:) as a rougher froth concentrate.

Third.Adding to the pulp in'the' flotation machine 0.30 gm. xanthatet andf4 dps. of frother consistingof amixture. ofparafline alcohols from 5 .to 10 carbon atoms. thereby recovering the copper in the form of a rougher froth concentrate.

maining in the machine) being considered wasteand drawn outof the machine. The rougher concentrates may be graded up as desired by methods known to the art.

I EXAIWPLE 13.

The following metallurgical results were 'ob-:- tained using the antimony agent and-treatinga;

75 mineral aggregate composed principally of .inol'ybdenite and other sulfldes such those of copper and iron:

500 gm. of general flotation concentrate (Utah Copper Co.) were subjected to flotation in the presence of an antimony agent (prepared by reacting 2 gm. SbaOa, 1 gm. KQH and 1 gm. 8 v

in aqueous solution) whereby a rougher molybde'nite concentrate and a rougher tailing were produced, the rougher molybdenite concentrate being subsequently cleaned, making'a cleanerv tailing and a cleaner concentrate.

A talcos e lead-zinc ore containing. galena,

sphalerite and pyrite was treated with lime and copper sulfate'and floated with sodium ethyl xanthate, a solution of thiocarbanilide in dicresyldithiophosphoric acid, and pine oil to give Fe and 1.1% insoluble, representing recoveries of 90.2% of the lead, 91.1% of thezinc and 97.0%

of the iron but only 4.4% of insoluble originally A lead concentrate was floated from a micaceous lead-zinc ore containing galena, sphalerite, and pyrite by the use of lime, sodium cyanide, copper sulfate, sodium ethyl xanthate, a solution of thiocarbanilide in dicresyldithiophosphoric acid, and pine oil. This concentrate, containing 43.1% insoluble mostly as micaceous material which floated readily with the sulfides and 19.6% Pb and 3.92% Zn, was conditioned with 0.37 lb./ton of a depressant formed by reacting in water 12 parts caustic soda with 9.0 parts sul fur, and 12 parts AS203 in 70 parts of hot water and then refloated with 0.6 lb./ton pine oil. The resulting concentrate assayed 43.9% of Pb, 3.8% Zn and 6.7% insoluble, representing a recovery of 89.7% of the lead and 1.2% of the zinc.

EXAMPIEIG From a carbonaceous gold ore assaying about 0.20 oz. Au/ton and about 1.5% C. and containinggold in association with pyrite, iron oxides,chalcopyrite and quartz a concentrate was floated using 0.3 lb./ton potassium ethyl xanthate, 0.03 lb./t n of a 1:1 mixture of sodium diethyl and disecondary butyi dithiophosphates and 0.05 lb./ton pine oil. This concentrate assayed 1,150 oz. Au/ton, 1.72% 0., and 64.7% insoluble and represented a recovery of 91.3% of the gold. This amount of carbon interfered with cyanidation oi the concentrate, causing reprecipitation of the gold to give cyanidation tailings assaying .53 oz. Au/ton.

A portion of-the concentrate was conditioned with 2.5 lb./ton oi'a depressant prepared by re-' acting a 1:1 mixture of Cat) and P285 at 70-80 C. in water to depress sulfides and refloated using in stages 0.12 lb./ton of a mixture ofv parafline alcohols from to .10 carbon atoms and 0.18 lb./ton fuel oil toremove the carbonaceous material. 89.7% of the goldv remained in the sulfide tailing while the major portions or the carbon were removed 'in the froth. The sulfide tailing was subjected to cyanidation to give a tailing of 0.23 oz. Au/toh.

' A 1:1 mixture 'ofclialcocite and sericite and a 1:1 mixture of chalcocite and pyrophillite (all minerals minus 150" mesh were floated as follows: 3

(a) With 0.25 1b./ton of a mixture ofparaiflnealcohols from 5'toj 10 carbon atoms alone and (b) With 0.25 lb./ton' of 'a'mixtureoi parafline alcohols from 5 i'o10 carbon atoms and 1 lb./ton of a depressant formed by reacting 10 parts CaO with 1.0 part P235 in 'water at 70-80 C.

(c) with 0.25 lb./ton of a mixture of parafline alcohols from 5' to 10 carbon'atoms alone and with 0.1 1b./ton sodium secondary butyl'xanthateand 0.1 lb./ton sodium secondary butyl dithlop 'p at a lb./ ton of the de- (a) As in (0) but with 2.5

pressant described in (b). 1 I

' tlhaleocite sefricite centfloated Treatment Chalcocite' 'Sericite z a: c 9010 02.0 a 9.3 91.1

chalcocite-Pyrophilite per cent floated Treatment Chaleocite Pyrophilite 2-? s? 0 88:9 9015 a 1123 I 88.4

. One part arsenic sulfide was reacted with 4 parts hydroxide in aqueous solution and dilutedto a total of 100 volume parts of water. This-depressantwas used".on a copper-molyb- ,denit concentrate 'obtained by the flotation treatment' pf a copper ore-from Utah. The foilowing testing' procedure was on this concentratet" 7 4 An aqueous'pulp of the'fl'otation concentrate containing 500 gm. dry solids was conditioned in a laboratory Fagergren flotation machine with 14.64 lb. per ton 66 B. sulphuric acid, then conditioned with 9.6 lb. per ton commercial lime (CaO). Nextfwas added suflicient depressant H to give 3.0 lb. per ton (AS203 basis) followed by 70' 0.16 lb. per'fton. inodifled burner oil and higher alcohol ,i'rother-"as required;- The froth was removed for a period of 7 minutes, constituting the rougher molybdenite' concentrate. The major portion of thecopper iron sulphides remained in the as the rougher tailing.

and plus 325 mesh) 11 The following table summarizes the metallurgical results obtained in this test:

Assays, Per Distribution, Nola:i Cent Per Cent Per t Product on Mos, Cu MoS| g gg:- ougher ailing Bought: M081 00110..

EXAIMPLE 19 A depressant was prepared by treating 5.0 parts A8236 with 50 volume parts of concentrated NHiOH. The mixture was agitated and allowed to stand overnight and then excess AS285 was removed. 30 ml. of the resulting solution were used in a test on the ore employed in Example 18. Other details of the testing procedure were the same as described in Example 18. The following metallurgy was obtained.

Assn Per Distribution 02:: Cent W t, Per

Product Per t On Cu Mos:

Head 1 1 Rougfi Tsilin Bougher M08; one- EXAMPLE 20 Aaae y r l Pcr Distribution,

We Per Cent Product Per t MoSi Cu MoSg Head g Rougher Telling Rougher MoSs Conc..

EXAMPLE 21 Assays, Per Distribution,

Cent Per Cent We t,

Product Per wt Cu M03: Cu Mos war s-rims 3% o a Rougher Mos, 00110.. 8.

EXAMPLE 22 56 lb. sulfur, 75 lb. NaOH and 50 gallons water were reacted by boiling. 75 lb. AS203 were then added and boiled with the mixture. A flotation test using this depressant in the procedure and on the concentrate described in Example 18 was conducted with the following metallurgical results:

Assays, Per Distribution, Wei my Ccnt Per Cent Product Per Cu MOS; Cu MOS! Heading 100. 00 35. 700 1. 86 100. 00 100. 00 Rougher Tailing 94. 81 37. 116 0. 02 98. 57 0. M Rougher MoS, Conc. 5. l9 9. 850 42. 10 l. 43 99. 14

EXAMPLE 23 A depressant was prepared by mixing 50 gallons of the depressant described in Example 20 and 25 gallons of the depressant described in Example 22. The resulting product was used in a. flotation test on the concentrate described in Example 1 and with the same testing procedure. Metallurgical results follow:

Assays, Distribution, ht, Per Cent Per Cent Product Per em Cu M081 Cu M08:

Heading 100. 0 32. 500 l. 50 100. 0 100. Rougher Telling 96. 2 32. 700 .05 99. 2 2. Rougher M081, Conc. 3. 8 6. 900 47. 20 0. 8 97.

The above reaction products are typical of the class coming under the invention. Any alkaliforming metal may be used in place of the calcium, sodium, and ammonium radical used in these examples. Salts of strong bases and weak acids can be reacted as well as the hydroxides. Alkali and alkaline-earth cyanides form depressants, with arsenic and sulphur, and with phosphorus and sulphur of unknown composition.

EXAMPLE24 The preliminary acid-lime treatment is not always necessary, particularly in treating ores; however, in treating concentrates containing residual collector agents such treatment is frequently essential in obtaining commercial results. This is demonstrated in the following two tests which compare the results obtained with and without the acid-lime treatment on the concentrate and with the testing method used in Example 18. The depressant used was that used in Example 23.

Heading:

Per Cent Cu 33.500 33.500 Per Cent MOS: 1.720 1.720

Rougher Tailings:

Per Cent Wgt 95.960 92.480 Per Cent Cu 34.000 34.400 Per Cent Distr. Cu 98.910 95.070 I Per Cent Mos: 0.070 0.060 Per Cent Distr. MOS: 3.530 3.190

Rougher Mos: Conc.:

' Per Cent Wgt 4.040 7.520 Per Cent Cu 9.000 21.900 Per Cent Distr. Cu 1.090 4.930 Per Cent Mos. 45.300 22.200 Per Cent Distr. MoSz 96.470 96.810

. 13 Agents added, lb. per ton:

Sulphuric Acid 14.6.4 .Lime (Commercial) 10.00 Depressant (AS203 basis) 3.00 3.000 Modified Burner Oil 0.16 0.160 Alcohol Frother 0.18 0.160

The above two tests show marked improvement in the grade of the rougher molybdenum concentratein both tests. While better results were obtained with the acid-lime treatment, good results, in fact nearly .1300 percent .increase in grade, were obtained withoutthe use of acid and lime. The quality of the froth favors the acid lime treatment.

- EXAMPLE 25 I A copper-molybdenum concentrate obtained by flotation treatment of a Utah ore was treated in 500 gm. Fagergren flotation machine. To the charge of about 500 gm. of concentrate (dry basis) and water were added the following agents in the amounts designated:

1 mLsulphuric (H2804) 66 B. 1 gm. lime (CaO) 25 mi. of the reaction produce (2 gm. C310 20 ml.

H20 and 1 gm. arsenic'sulphide) made up to 50 ml. for testing.

' 2 dps. molybdenite collector (burner 01.1. modified) In the flotation that followed, substantially all the molybdenite was removed as a froth concen- Y trate, making (1) a rougher tailing'and a rougher concentrate. The rougher concentrate was cleaned. making (2) a cleaner tailing and (3) a cleaner concentrate containing substantially all the molybdenite, the depressed copper and iron sulphides remaining in the rougher tailing The results of this test may be seen from the following metallurgical tabulation:

Per Cent Assays Per Cent Distr. Per Cent eight Cu MOS: On Most Heading 100. 31. 76 1.130 100.00 100. 00 Rougher Tailing. 83. 68 31. 50 040 83.19 2. 34 Cleaner Tailing 14. 17 37. 2. 280 16. 56 22. Cleaner Concentr. 1. 95 4. 20 56. 100 75.

EXAMPLE 26 14-Day Aver-' Conditioning Agents, Per Ton gf g fi'l b 10.00 Lb. Lime Heading:

Per Cent Cu 34. 543

Per Cent M082 1.49 Kougher Taiiing:

Per Cent Wat; .4... 94. 01

Per Cent Cu 35. 363

Per Cent Di tr C 98.46

Per Cent M08 0. 075

Per Cent Distr. M08 3. 44' Rougher MoS: Concen ate:

Per Cent Wgt 5. 99

. -P.er Cent Cu &68l' Per Cent Distr. Cu. 1.54 Per Cent MOS: 27.54

Per Cent Distr. MOS2..., 96.56 Agents, Lb. Per Ton:

Depressant 3.0

Alcohol Fr'other ,0. 16

1 -..nxdMPm27 Samples of copper-molybdenum concentrate obtained by the flotation. of a Utah ore were treated as in Example 18 with a depressant consisting of a 1:1 mixture of a NaSH and AszQ: in solution A flotation test using 4.8 lb./ton of depressant according to the procedure of Example 18 was'conducted. The feed to flotation assayed about 33.5%- cu and.1. 27% M082. Metallurgical results'follow:

cone-per cent Cu assay... 22.81

Cone-per cent M08: assay 16.09 Conc.-per cent .Cu-distributiom; 4.47

Cone-Der cent MoSz-distribution. 85.64

A cleaner float was] conducted on the concert-y trate from this test to produce a concentrate assaying 9.72% Cu and. 28.04% M082, representing .a recovery of about 1%;01 the total copper and 1 74.71% of the total MoSa.

It'was found that c alcium chloride was an efl'ective conditioning agent and maybe used in place i of acid. The.14-,day.samples'described in Example 23 were conditioned with 6.0 lb./ton calcium":

Heading: Per cent Cu..... 34.543

Per cent M0S2 1.49

Rougher tailingz" Per cent w'gti 1 92.90 Per cent -Cu 35.507- Per cent Cudlst; 97.50 Per cent M0S2 0.055 Per centMoS2'-dist' 2.94

Rougher Mos: cone:

Per cent wt 7.10 Per cent Cu; 11.936 Per cent Cu-dist 2.50 Per cent MoSz 23.43 Per cent MoSz-dist 97.06

EXAMPLE 2;

Cther efleetive compounds for conditioning the flilpulpl'prior to the depression of copper minerals art: magnesium chloride, magnesium sulfate,,S bdium chloride, sodium sulfide, ammonium ch16 ride, bariumf-chloride, calcium acetate, and calcium hypochlorite. Following the conditioning operation with these compounds,'iirne' is added for-pH adjustment.

Examples'of the use of several of these condi-- agents follow employing 500 gram charges Utah copper co. general flotation concen- 7.0 trate ina laboratory Fagergren flotation mau e fil h .0 6 -;/t .01. modified burner.. all

, 2,499,986 15 16 (molybdenite collector) and higher alcohol reacted residue was filtered oil and discarded. frother. Metallurgical results follow: The tests described below compare equal quantitiesof both depressants (AsaO: basis) in the treatment of a copper-molybdenum concentrate I gY g b gm 5 obtained by flotation ot a Utah ore. Product weight en 7 er en Per Cent Cu M08; Cu Mos;

' Original 223 Depreaaant Prod ct CQNDITIONER, 2.0 GM. MgClg; MODIFIER, 0.5 GM. LIME 1o Heading:

Headinflmlc.) 100.00 28.443 1.01 100.00 100.00

Rougher tailing 00.01 30.100 0.01 00. 11 3.32 g: saga- 1- Roughcr eonc 9.33 11.850 19.80 3.89 96.68 Rougher ag gel" gauge 1315.80 CONDITIONER 2.0 GM. CALCIUM ACETATE er an L450 Per Cent Distr. Cu.-- 97. 32

MODIFIER, 1.0 GM. LIME Per Cent Mos, 0.08

R P r Csnt Disttr. 2110s. 0.40 a.

H din 0111c. 100.00 02. 202 1.03 100.00 100.00 mice R ugh Emmi. 95.88 33.100 0.00 011.55 4. 41 3; cum 3- Rougher cone 4.12 11.300 44.80 1.45 95.53 Per Cent mam OIL 2'68 CONDITIONER 0.1 GM. 0030102140 PLUS 1.5 GM. C001,; er en 3 1 Agents added (lb. per ton): MCDIFIER, 0.5 GM. LIME Sulphuric Acid m2 132 L1 0.00 0.00

Heading (01110.)... 100.00 30.400 2.05 100.00 100.00 3 2g Roughcr tailing.. 04.85 01.500 010 90.00 4.04

Rougher concentrate" 6.15 11.300 37 90 1.91 95.36 .16

D TIO ER 1.5 GM. CALCIUM HYPOCHLORITE; CON I N M01 1r1ER,0.sCM.L1ME The same depressant was reacted with zinc.

sulphate and the reaction product added to the neadgl (c1510.) 1 51.30 21 130% 102.01 1 pulp. The feed to the flotation machine was ing Utah Copper Company general flotation concen- R he concentrate" 6.06 16.000 30.00 2.67 97.&

9" trate. Details of the testing are listed below.

EXAMPLE 29 Depressant Onginai Reached Heavy metals may replace the alkali-forming Depressant 11% metals in the preparation of depressants. For n 1 example, the depressants may be prepared as de- H scribed and then reacted with a met l salt prio P, d 310 3&3,

to adding to the pulp as in the'following com- 40 no gg g q 1.513 1.513

pal'fltive tests: 18 95 7 9 1 Identical 500 gm. samples oi the concentrate 33.0 50 1 described in Example 18 were floated in exactly the same manner, except that in the first test lg g glo l 0.00 0.15

the depressant used in Ex mpl 2 w mp d c w and in the second test the reaction product of 3; 82 ;23

Acid-lime con ioning was emp oy er on o 1 A nts added b. rton tests as shown in the table Of results. s g m f 132 732 Lime 6.00 6.00 Depressant (A1110: basis).. 3.00 3.00 Modified Burner Oil 16 .16 or Dfigmnt HigherAlooholFrother .16 -16 I Depressant With 011804 7 I Other metals tested include iron, lead, chromi-j fieaging to um um um, aluminum, molybdenum, etc. The products .3; 33. L'g L178 L178 of the reactions of the above depressant with the .nou her 'rsi u 95 M m 93 following are specific examples: ferrous sulphate, .3; fifl fjjjjjjj 351600 05,450 lead nitrite, chromium nitrite, aluminum sulgg; a' g-z 53: 6o phate, ammonium molybdate. R Per C'nt Distirifiol. 3.25 3.29

ouzher ODCGD ae:

Per Cent Wgt 4.00 3.01 EXAMPLE 31 Per Cent Cu 18.36 12.40 988112113435 1355 $13 0th t is 1 th lkall r rmin er on o 1 er me a may rep ace e a o g JE.E ZE %EZ 96 96 71 metals in the preparation of depressants. For

iuhll lagmric .401 7 -35 kg example, the depressants may be prepared as de- De .5.;;.1'(13;6; is I 1 M0 scribed and then reacted with a metal salt prior M0 med 16 to adding to the pulp as in the following com- F H1gher Alcohohc rother 16 16 paratlve tests:

I Identical 500 gm. samples of the concentrate LE 30 7 described in Example 18 were floated in exactly EXAM? the same manner, except that in the first test A depressant was prepared by reacting 0.2 gm. the depressant used in Example 20 was employed cuS (finely powdered) with 8 cs. ot-the depreB- and in the second test the reaction product or this sent described in Example 29. A'trace of undepressant with copper sulfate was used. Acid- Reacmd WithZnSOc Original Depressent Depressent 1a I following the method of Example 81. Details oi. the testing are listed below.

As illustrated In obtaining the results, given In the first test this alkali type depresthe second test copper in the 6 m- -h m a H mm m mam ee 1 m r n am. am t t R d .1 mmm w b dmmm pa a m t a am a peh t d s ah efi e wd mdmt et n 8 tiefl I n n b mem rr w 3 t S D a 8 I u mfl ee ltw w r an an e I m m n. m et mw I u r mod hm n muw nu Woe ms g .vt S e er. 2 m m m awm mm sw :r :3 w n ew I MmIcfi mmdmm um m m nm mm un n eHewe d c ee wa wam mm mowmw m mmm cMmwCDMDmwCDMD e m m 0 mm tteut-t-flt-O-O-tt -mwme u s ee mmmmmmm wmm b fi m a d wwwmcccc cmccc m mmefl ww mw riff fffr. 0: pn aaaaa fimm mmmw m mww mmmm i v. n n a mwabswmw mmwmmm 5 1 m M m mm mmwmu awmwm mm .1. 7 6 3 0. u 2. 0 t 00 mm tat m 2 m lime conditioning was employed in both tests as shown in the table of results.

Per Cent Cu. Per Cent MOS Rouxher Tmling Per Cent Wgt. Per Cent 0a.-

Per Cent Mos Per Cent Distr. MoS;.. Rmmher Concentrate:

Heading:

Per Cent Wgt. Per Cent Cu Per Cent Distr. C Per Cent M08 0...

Per Cent Distr. MoS: Agents added (lb. per ton):

Sulphuric Acid EXAMPLE 32 The metallic salt used in forming a metallic type depressant need not be soluble in water as CuS (finely powdered) with 8 cc. of the depressant described in Example 20. A trace of unreacted residue was filtered off and discarded. The tests described below compare equal quantities c a e r y n .D n d u e 0 IN m m n. im p. i m Imam m :aom .IW rF t m l hn me t h V. mm m m dm a m... a m mms d mmMm m dA n i m m anna we? E ma m m mama. mam m aw 1.742% MOS:

1%116! Telling: er CentW EXAMPIE 35 Several metal salts were added to the pulp as described in Example 34. The testing method was F that used in Example 31 and the alkali depressant was that used in Example 20. The metal Per Cent Distr. MoS1....-..---

W0 1% m mo t cDMmW ttt t mmmmm cc 0 LN-AG! mPmmm o R 5 4 m mm a mm mm "me an m 03 AMSOA):

mmawu dehmw an improvement Or(N03):

%u.mw n manna u mw ZnSOr Pb(N03) was.

salts were added after the treatment with acid as indicated above. In the first test the alkali type depressant only was used in the concentrate grade of Moss was obtained in all following tests employing the metal salts.

Heading: 35.91% Cu None Original Depressant ressants (AS203 basis) in the treatpper-molybdenum concentrate obtained by flotation of a Utah ore according to the procedure of Example 31.

of both dep ment of a co Heading:

Per Cent Cu Per Cent MOS, Rougher Tailiggs:

Per Cent gt. Per Cent Cu Per Cent MoSz Per Cent Distr Rougher Concentrate:

Per Cent Wat..." Per Cent Cu Per Cent Wt. Per Cent Cu Thus, even with an insoluble metallic compound such as coppersulfide a potent depressant was prepared.

EXAMPLE 33 The same depressant was reacted with zinc sulphate and th reaction product added to the pulp,

Metal Salts Usedm.

Metal Salt Added (lb. per

ton)... Rougher Telling:

Rougher Concentrate:

Per Cent Wt.. Per Cent Cu.

Per Cent MoB:..-... Per Cent Distr. MoSzm.

This application is in part a continuation of our earlier now abandoned copending application Serial No. 530,350, filed April 10, 1944.

We claim:

1. A froth flotation process which comprises subjecting an aqueous pulp containing a mineral included in the group consisting of molybdenum sulfide, carbon, strongly hydrophobic hydrous aluminum-containing silicates and strongly hydrophobic hydrous magnesium silicates and at least on sulfide mineral, to froth flotation in the presence of an inorganic compound of an element selected from the group consisting of phosphorus. arsenic and antimony, said compound containing bivalent sulfur and an inorganic cation, said compound being present in amounts suificient to depress the sulfide minerals without substantial depression of molybdenum sulfide, carbon, strongly hydrophobic hydrous aluminum-containing silicates and strongly hydrophobic hydrous magnesium silicates and an oil collector for said minerals selected from the group consisting of hydrocarbons, water insoluble alcohols and mixtures. the collector being present in sufiicient amounts to fioat molybdenum, sulfide, carbon, strongly hydrophobic hydrous aluminum-containing silicates and strongly hydrophobic hydrous magnesium silicates. removing a concentrate relatively rich in the said minerals and relatively poor in the depressed sulfide mineral.

2. A process according to claim 1 in which the depressant is a compound of phosphorus.

3. A process according to claim 2 in which the only mineral floated in the presence of the inorganic compound of phosphorus is molybdenite.

4. A process according to claim 3 in which the ore is conditioned with an acid and an alkali prior to flotation.

5. A process according to claim 4 in which the ore is additionally conditioned with a soluble salt 40 of calcium.

6. A process according to claim 1 in which the only mineral floated in the presence of the inorganic compound of phosphorus, arsenic or antimony is molybdenite.

7. A process according to claim 6 in which the ore is conditioned with an acid and an alkali prior to flotation.

8. A process according to claim 7 in which the ore is additionally conditioned with a soluble salt of calcium.

9. A process according to claim 1 in which the depressant is a compound of arsenic.

10. A process according to claim 9 in which the only mineral floated in the presence of the inor ganic compound of arsenic is molybdenite.

11. A process according to claim 1 in which the ore pulp contains molybdenite and a sulfide of copper.

12. A process according to claim 11 in which the depressant is a compound of phosphorus.

13. A process according to claim 12 in which the depressant is a reaction product of phosphorus pentasulfide and an alkali-forming hydroxide.

14. A process according to claim 13 in which the alkali-forming metal hydroxide is sodium hydroxide.

15. A process according to claim 13 in which the alkali-forming metal hydroxide is calcium hydroxide.

CHARLES M. NOKES. CHARLES G. QUIGLEY. ROBERT 'r. PRING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Mellor: Inorganic and Theoretical Chemistry, vol. 8, pages 1056 and 1057. Copy in Div. 59. 

